What It Means
Gamma is an option Greek that measures how fast delta itself changes for every ₹1 move in the underlying asset. If delta tells you how much an option's premium moves right now, gamma tells you how much that sensitivity is about to change.
How It Works
Gamma is highest for at-the-money options and grows sharply as expiry approaches, which is why option prices near expiry can swing violently on small underlying moves — delta itself is shifting fast underneath. Deep in-the-money or deep out-of-the-money options have low gamma because their delta is already close to its extreme (near 1 or near 0) and has little room left to change. Option sellers watch gamma closely because a high-gamma position can flip from comfortably profitable to sharply losing within minutes as the underlying moves.